With rapid development of wireless communications technologies, various intelligent terminals present an explosive growing trend, plentiful and diversified data services are also constantly emerging, and high-rate service requirements of users pose a severe challenge to conventional cellular networks. In a heterogeneous cellular network technology, a low-power node, such as a small cell (Small Cell), a femto cell (FemtoCell), or a pico cell (PicoCell), is introduced within a coverage area of a conventional macro cell, so as to pertinently strengthen coverage of a specific area and form multi-layer network coverage. This can effectively achieve QoS assurance for the user and improve system resource usage.
Introduction of small cells changes a network topology structure, and the small cells feature dense deployment and flexible locations. Therefore, an ultra-dense network (Ultra-dense Network, UDN) is formed. There are basically two networking manners for macro base stations and micro base stations in a UDN system: a homogeneous manner, namely, a networking manner supporting deployment that is based on a same frequency channel number; and a heterogeneous manner, namely, a networking manner supporting deployment that is based on different frequency channel numbers. Different networking manners pose a difficulty and challenge to a handover control technology of a UDN network. In a heterogeneous network, a network structure is quite complex. For example, when UE moves within a macro base station, the UE may enter a small cell and leave the small cell many times. UEs at different speeds have different handover performance in moving across different target cells. UE at an excessively high speed may cause a handover failure. In addition, as a radius of a target cell decreases rapidly, UE is handed over to the target cell more frequently, resulting in a greater handover delay. This reduces network performance and affects user experience. Therefore, in the UDN system, because dense cell deployment leads to a new handover problem, how to comprehensively consider a handover delay and user communication experience and design a more effective handover method becomes a problem that urgently needs to be resolved.